CN114501988B

CN114501988B - Device for detecting insect larvae and adults in stored products by sensing volatile and chemical pheromones

Info

Publication number: CN114501988B
Application number: CN202080070560.8A
Authority: CN
Inventors: 尼古拉斯·约瑟夫·斯米兰尼奇; 赛缪尔·费尔斯通·赖克特; 弗兰克·伯纳恩·图德龙
Original assignee: Sensor Development Co
Current assignee: Sensor Development Co
Priority date: 2019-09-03
Filing date: 2020-08-26
Publication date: 2023-04-07
Anticipated expiration: 2040-08-26
Also published as: CN114501988A; CA3150150A1; WO2021045943A1; BR112022004075A2; TW202126170A; EP4025907A1; ZA202203764B; AU2020341335A1

Abstract

A cost-minimized, high-precision portable device for detecting the presence of insects at various stages of life, including the egg stage, in stored products by sensing gas-phase markers such as volatile pheromones, semiochemicals and kairomones. The methods, devices, and systems disclosed herein utilize a sensor array configured to simultaneously measure multiple target markers and filter background gas while remaining compact, highly accurate, and easy to operate.

Description

Device for detecting insect larvae and adults in stored products by sensing volatile and chemical pheromones

Technical Field

The following disclosure relates generally to the field of insect and pest (insect infestation) detection, chemical sensing, gas detection, volatile organic compound analysis, gas sensing microchip arrays, and methods and apparatus related thereto. It finds particular application in techniques relating to the detection of insects in stored food and other products or materials with high sensitivity and selectivity.

Background

Storage product insects ("SPI") are commonly found to feed on finished foods, food ingredients, or infest equipment that prepares, processes, packages, and stores food. Economic losses from these pests in processing, transportation and storage systems can be millions of dollars in each contamination, product recall, consumer complaints/litigation, and pest control application event (Arthur et al, 2009). In addition, some SPIs have health effects when accidentally eaten, resulting in gastric stress disorders in infants and the elderly (Okamura, 1967).

Current insect detection relies on flash light inspection and the use of traps with a variety of synthetic pheromone lures and traps to capture adult SPI. Pheromones are volatile organic compounds ("VOCs") emitted from individuals of male or female species. Pheromone lures and traps are dependent on insect activity, and this can be significantly affected by temperature. Pheromone volatility, quantity/mass, and human activity and insect dynamics interact with these elements, resulting in constantly changing trap data. The interpretation of trap trapping is based on a small sampling of the population (2% to 10% or less). This makes it more difficult to detect and repair the pests.

Indian meal moth ("IMM") is the most common storage product insect throughout the United states (Mueller, 1998; resener 1996). This is an insect that is more common than any other insect in food and grain stored in the united states. Adult IMMs can be found almost anywhere in the temperate regions of the world. Furthermore, it is one of the insect pests that causes the most damage in the united states and europe. This insect survives well in our environment for two reasons: 1) Females lay large numbers of eggs during their short life; and 2) its ability to genetically alter or adapt to survive the pesticides used by humans to protect their food (resistance). IMM is considered to be the most resistant insect known to humans. During the fifty years, the genetic composition of the insect has changed to combat the common pesticide Malathion (Malathion). In the 70's of the 20 th century, IMM began to show signs of resistance to this common pesticide. IMM developed 60000 times resistance to this pesticide.

IMMs are most commonly found on finished foods, food ingredients (e.g., stored wheat products, ground/processed wheat) and other stored products (e.g., ground cereal products, flour, bran, pasta products, spices), or equipment that infests in preparing, handling, packaging or storing food. IMM larvae are destructive life stages of insects that feed greedily. The larvae are very mobile and can continuously search for new food sources. The value of food is impaired by the food they consume, the feces they produce, and the bands (webbing) that the larvae leave as they move.

In addition, IMMs are often precursors to other storage product insects. The unprocessed IMM intrusion may be an indicator that other SPI intrusions are imminent (Mueller, 2016). The five most common Storage Product Insects (SPIs) include Indian meal moth (Pludia interpunctella), dermatophagoides (Trogopterma variable)), flour beetle (Tribolium spp.), grain beetle (Oryzaphius spp.), and tobacco beetle (Lasioderma serricorn) (Mueller, 1998; hagstrum and Subramanyam, 2006). Economic losses from these pests during handling, transportation and storage can be millions of dollars in each pollution, product recall, consumer complaints/litigation, and pest control application event (Arthur, 2009). There is currently no efficient, low cost method to monitor and detect them.

Several SPI pheromones have been identified, but they are not commercially available due to short shelf life and production cost (Phillips et al, 2000). The compounds are unique, but can attract species competitors, for example, in the storage food moth population and the tropisodes (Trogoderma) complex. Monopheromone (Z, E) -9, 12-n-tetradecadienyl acetic acid is the major pheromone of the Plodia genus (Plodia), but attracts the other three food moths of the Pink moth (Ephestia) species. The pheromone compound R, Z14-methyl-8-hexadecenal is a major component that attracts warehouse beetles (trogloderma variabilis), but will also attract three other common species of the genus pissodes, including the pestiferous pests (Khapra beetles, trogloderma grandium). Several flour beetle species (Triboum species) were attracted to the mono-compound 4, 8-dimethyldecanal, two grain beetle species (Oryzaephius species) were attracted to (Z, Z) -3, 6-dodecene (Dodecadien) -11-lactone, but the pheromone (4S, 6S, 7S) -4, 6-dimethyl-7-hydroxynonenoic acid-3-one of the tobacco beetles (Lasioderma sericorne) was unique to the species.

Furthermore, for possible target semiochemicals and/or kairomones (kairomones), these are high molecular weight VOCs. As a result, their vapor pressure and concentration in the headspace of the storage product that is infested can be low and therefore more difficult to detect.

Accordingly, it is desirable to eliminate variability and uncertainty in detecting pest presence/absence, abundance, and location by using methods, devices, and systems that can detect and measure concentrations of a variety of pheromones. In addition, it would be desirable to provide methods, devices and systems that sense their semiochemicals and/or kairomones in a similar manner, not only to detect insect larvae but also to detect insect eggs. By allowing detection of earlier life stages (e.g. eggs), the amount of loss of stored product can be limited, as most damage is caused by insects during larval stages rather than during adults. The threshold concentration may be established to instantly determine whether the most common SPI is present in a trailer, land/sea container, bulk shipment, packaging material tray, or storage room. It is also desirable to provide the ability to detect VOC concentration gradients that can help locate and precisely locate structures, wall voids, cracks and crevices or SPI intrusions within a device. Furthermore, it would be desirable to provide a handheld device that would eliminate most of the dependency of insect mobility and environment as a factor affecting activity from the SPI monitoring model.

Is incorporated by reference

The following references are mentioned, the disclosures of which are incorporated by reference in their entirety:

Arthur F.H.Johnson J.A.Neven L.G.Hallman G.J.Follett P.A.(2009).Insect Pest Management in Postharvest Ecosystems in the United States of America.Outlooks on Pest Management,20:279-284.

Hagstrum D.W.and Subramanyam B.(2006).Fundamentals of Stored-Product Entomology.St.Paul:AACC Int.

Mueller,David K(1998).Stored Product Protection:A Period of Transition.Insects Limited,Indianapolis,Ind.

Okumura,G.T.(1967).A Report of Canthariasis and Allergy Caused by Trogoderma(Coleoptera:Dermestidae).California Vector Views,Vol.14No.3,pp.19-22.

Phillips,T.W.,Cogan,P.M.and Fadamiro,H.Y.(2000).Pheromones in B.Subramanyam and D.W.Hagstrum(Eds.).Alternatives to Pesticides in Stored-Product IPM,pp.273-302Kluwer Academic Publishers,Boston,MA.

Resener,A.M.(1997).National Survey of Stored Product Insects.Fumigants and Pheromones,Issue 46,pp3-4.

disclosure of Invention

Disclosed in various embodiments herein are low cost and high precision methods, devices, and systems for detecting one or more target volatile organic compounds ("VOCs") based on a target fluid stream (e.g., an air sample) sampled from an area proximate to a stored product to identify pests of the stored product (e.g., food). The disclosed methods, systems, and devices are designed to provide early detection capability, enabling rapid response to threat of infestation (e.g., cleaning, freezing, fumigating, etc.). In addition, these systems and devices have minimal cost and high accuracy, enabling widespread use of real-time, non-invasive detection of insect eggs, larvae and/or adults in the environment of stored products.

According to a first embodiment of the present disclosure, there is provided a method of identifying stored product pests by detecting one or more target VOCs in a target fluid stream, the method comprising the steps of: heating, via a device comprising a plurality of VOC sensors, at least one of the plurality of VOC sensors to at least a first operating temperature; contacting one or more VOC sensors with a target fluid stream; determining a set of conductance change values corresponding to each of the one or more VOC sensors contacting the target fluid stream; and determining a concentration of a gas component of the one or more target VOCs within the target fluid stream based on the set of conductance change values. Further, each VOC sensor may include: a substrate having a first side and a second side; a resistive heater circuit formed on a first side of the substrate; a sensing circuit formed on the second side of the substrate; and a chemically sensitive film formed on the sensing circuit at the second side of the substrate. In particular embodiments, the method can include correcting the baseline resistance of the VOC sensor to an earlier baseline value after sampling the VOC marker in the fluid stream, which can be accomplished by adjusting the operating temperature of one or more VOC sensors after each sampling of the target VOC.

In accordance with another embodiment of the present disclosure, there is provided an apparatus for detecting one or more target VOCs in a target fluid stream, the apparatus comprising a sensor array having a plurality of VOC sensors, wherein each VOC sensor comprises: a substrate; a resistive heater circuit formed on a first side of the substrate; a sensing circuit formed on the second side of the substrate; and a chemically sensitive film formed on the sensing circuit located on the second side of the substrate, wherein at least one of the plurality of VOC sensors is configured to detect the presence of egg-specific VOCs.

According to yet another embodiment of the present disclosure, there is provided a system for identifying pests on a stored product, the system comprising: a test chamber enclosing the sensor array; an air delivery unit configured to retrieve and deliver a fluid flow to a test chamber; a controller operatively connected to the air delivery unit and the sensor array. The sensor array includes a plurality of VOC sensors, and the controller is configured to: operating the air delivery unit to withdraw the fluid flow from the target area and deliver the fluid flow to the test chamber; operating the sensor array to measure the conductance of one or more of the plurality of VOC sensors; determining a set of conductance change values corresponding to each of the one or more VOC sensors; and determining a concentration of the gas constituent of the one or more target VOCs within the fluid stream based on the set of conductance change values. Further, at least one of the VOC sensors may be configured to detect the presence of egg-specific VOCs.

Drawings

The subject disclosure may take form in various components and arrangements of components, and in various steps and arrangements of steps. The drawings are only for the purpose of illustrating preferred embodiments and are not to be construed as limiting the subject disclosure.

Fig. 1 is a flow chart illustrating a method of identifying pests according to one embodiment of the present application.

Fig. 2A-2B are flow charts illustrating another method of identifying pests according to another embodiment of the present application.

Fig. 3 is a block diagram illustrating a system configured to perform the methods disclosed herein according to one embodiment of the present application.

Fig. 4A-4B are illustrations of a first side (fig. 4A) and a second side (fig. 4B) of a single VOC sensor according to certain embodiments of the present application.

Fig. 5 is an illustration of a single VOC sensor suspended in a rack according to one embodiment of the present application.

Fig. 6 is a cross-sectional view of a representative side view of a sensor array including a plurality of VOC sensors according to one embodiment of the present application.

Fig. 7 is a perspective view of a device shown in accordance with certain aspects of the present disclosure.

FIG. 8 is a block diagram of an intrusion detection system according to one embodiment of the present application.

Fig. 9A-9D are graphs illustrating the sensitivity of a VOC sensor array to various target volatile organic compounds according to one embodiment of the present application.

Fig. 10A-10C are graphs showing the response of a first VOC sensor to the presence of three target storage product insects ("SPI"), according to one embodiment of the present application.

Fig. 11A-11C are graphs showing the response of a second VOC sensor to the presence of three target storage product insects ("SPIs"), according to another embodiment of the present application.

Fig. 12A-12C are graphs showing the response of a third VOC sensor to the presence of three target storage product insects ("SPIs"), according to one embodiment of the present application.

Fig. 13A-13C are graphs showing the response of a fourth VOC sensor to the presence of three target storage product insects ("SPIs"), according to one embodiment of the present application.

Fig. 14A-14D are graphs showing the response of four VOC sensors to changes in the presence of three target storage product insects ("SPI") according to one embodiment of the present application.

FIG. 15 is a graph illustrating the response of a sensor to the number of cocoons in a stored food test example.

Fig. 16A to 16C are graphs showing changes over time in the baseline resistance curve of a specific sensor chip.

Fig. 17A to 17C are graphs showing the net resistance of the sensor chip in relation to the number of larvae in insects, larvae and cocoons.

Fig. 18 is a graph showing the response of a palladium-catalyzed sensor chip to NOW insects at different life stages.

Fig. 19A-19G are graphs showing the response of VOC sensors to the presence of certain insects at different stages of life.

Detailed Description

In the following specification and the claims which follow, reference will be made to a number of terms which shall be defined to have the following meanings.

Definition of

In the following specification and the claims which follow, reference will be made to a number of terms which shall be defined to have the following meanings. Although specific terms are used in the following description for the sake of clarity, these terms are intended to refer only to the particular structure of the embodiments selected for illustration in the drawings, and are not intended to define or limit the scope of the disclosure. It should be understood that in the following drawings and description, like numerals designate like components having the same functions. It should be further understood that the drawings are not drawn to scale.

The singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise.

The term "comprising" is used herein as requiring the presence of the referenced components/steps and allowing for the presence of other components/steps. The term "comprising" should be interpreted as including the term "consisting of 8230; …" consists of ", which only allows the presence of the named components/steps.

Numerical values should be understood to include numerical values which are the same when reduced to the same number of significant figures and numerical values which differ from the stated value by less than the experimental error of conventional measurement techniques of the type described in the present application to determine the value.

All ranges disclosed herein are inclusive of the recited endpoints and independently combinable (e.g., a range of "from 2mm to 10mm" is inclusive of the endpoints, 2mm and 10mm, and all intermediate values).

The term "about" may be used to include any numerical value that can be varied without changing the basic function of the value. When used with a range, "about" also discloses the range defined by the absolute values of the two endpoints, e.g., "about 2 to about 4" also discloses the range "from 2 to 4". More specifically, the term "about" may refer to ± 10% of the indicated number.

The terms "ppm" and "ppb" are to be understood as meaning "parts per million" and "parts per billion", respectively. As used herein, "ppm", "ppb", and the like refer to volume fraction, not mass fraction or mole fraction. For example, a value of 1ppm may be expressed as 1 μ V/V, and a value of 1ppb may be expressed as 1nV/V.

As used herein, the term "stored food product" should be understood to mean food products stored in a container (e.g., made of paper, cardboard, plastic, foil, cellophane, etc.) of some sort, and should be understood to include, for example, without limitation, flour, grains, cake flour, corn meal, rice, pasta, cookies, seeds, dried beans, popcorn, nuts, chocolate, raisins and other dried fruits, spices, milk powder, tea leaves, bacon, bird feed, dried pet food, and almonds (e.g., shelled almonds).

The present disclosure may be understood more readily by reference to the following detailed description and the various figures discussed therein.

Method

Disclosed herein are methods for determining the presence of insect pests in a stored product by detecting the presence of one or more target volatile organic compounds ("VOCs") (e.g., certain semiochemicals, kairomones, and/or pheromones of various stored product insects ("SPIs)) with high sensitivity and high selectivity.

Referring to fig. 1, a method 100 for identifying pests of a stored product by detecting one or more target volatile organic compounds within a target fluid stream is provided. The method comprises the following steps: providing a device comprising a sensor array having a plurality of VOC sensors (S110); heating one or more of the plurality of VOC sensors to at least a first operating temperature (S115); contacting one or more VOC sensors with a target fluid stream (S120); determining a set of conductance change values corresponding to each of the one or more VOC sensors in contact with the target fluid stream (S125); and determining a concentration of a gas component of the one or more target VOCs within the target fluid stream based on the set of conductance change values (S130). According to a first embodiment of the method 100, each VOC sensor of the sensor array comprises: a substrate; a resistive heater circuit; a sensing circuit; and a chemically sensitive film formed on the sensing circuit. In some embodiments, the resistive heater circuit may be formed on a first side of the substrate, the sensing circuit may be formed on a second side of the substrate, and the chemically sensitive film may be formed on the sensing circuit on the second side of the substrate.

In particular embodiments, the method 100 includes measuring the signal conductance of the one or more VOC sensors after the one or more VOC sensors contact the target fluid stream. That is, the set of conductance change values may be determined based on a difference between the signal conductance of each of the one or more VOC sensors contacting the target fluid stream and the baseline conductance of each of the corresponding VOC sensors. In some embodiments, the baseline conductance of the one or more VOC sensors is measured when the one or more VOC sensors are in an environment without any target VOCs.

In a preferred embodiment, the target fluid flow is a sample of air taken from the vicinity of the stored product being evaluated for potential infestation. That is, the target fluid stream may be a gas sample from the headspace above the storage product of interest.

Method 100 begins at S105 and ends at S135, however, in certain embodiments, method 100 may be repeated (e.g., repeating steps S110 through S130) by sampling multiple target fluid streams (e.g., air samples) from within multiple adjacent areas of the storage product (S) being evaluated. That is, method 100 may identify a gradient of potential pests by sampling one or more target fluid streams at multiple distances from the storage product(s) (e.g., a distance of less than about 1 foot from the storage product; a distance of between about 1 foot and 2 feet from the storage product; a distance of between about 2 feet and 3 feet from the storage product; etc.).

In other embodiments, the one or more target VOCs are semiochemicals, kairomones and/or pheromones associated with one or more insects (e.g., SPI). In particular, the one or more target VOCs may be semiochemicals, kaempferia galamensis, and/or pheromones associated with, for example, red flour beetles, sawtooth grain beetles, warehouse beetles, indian meal moth, navel orange borer, mediterranean pink borer, pink spot borer (known as tropical warehouse moth), wheat moth, and/or tobacco beetles. In particular embodiments, at least one of the one or more target VOCs within the fluid stream may be selected from the group consisting of: 11, 13-hexadecadienal, 4, 8-dimethyldecanal; (Z, Z) -3,6- (11R) -dodecen-11-olide; (Z, Z) -3, 6-dodecenolactone; (Z, Z) -5,8- (11R) -tetradecadiene (Tetradecadien) -13-lactone; (Z) -5-tetradecene-13-lactone; (R) - (Z) -14-methyl-8-hexadecenal; (R) - (E) -14-methyl-8-hexadecenal; gamma-ethyl-gamma-butyrolactone; (Z, E) -9, 12-n-tetradecadienylacetic acid; (Z, E) -9, 12-tetradecadien-1-ol; (Z, E) -9, 12-tetradecadiene; (Z) -9-tetradecene acetate; (Z) -11-acetic acid hexadecenyl ester; (2S, 3R,1' S) -2, 3-dihydro-3, 5-dimethyl-2-ethyl-6 (1-methyl-2-oxobutyl) -4H-pyran-4-one; (2S, 3R,1' R) -2, 3-dihydro-3, 5-dimethyl-2-ethyl-6 (1-methyl-2-oxobutyl) -4H-pyran-4-one; (4S,6S,7S) -7-hydroxy-4, 6-dimethylnonan-3-one; (2S, 3S) -2, 6-diethyl-3, 5-dimethyl-3, 4-dihydro-2H-pyran; 2-palmitoyl-cyclohexane-1, 3-dione; and 2-oleoyl-cyclohexane-1, 3-dione.

Referring to fig. 2A and 2B, a method 200 of identifying pests of a stored product by detecting one or more target volatile organic compounds within a target fluid stream is provided according to another embodiment of the present disclosure. The method 200 begins at S202.

In step S204, a device is provided that includes a sensor array having a plurality of VOC sensors. Each VOC sensor of the sensor array comprises: a substrate; a resistive heater circuit; a sensing circuit; and a chemically sensitive film formed on the sensing circuit. In some embodiments, the resistive heater circuit may be formed on a first side of the substrate, the sensing circuit may be formed on a second side of the substrate, and the chemically sensitive film may be formed on the sensing circuit located on the second side of the substrate.

In a particular embodiment, the sensor array includes a plurality of different VOC sensors. That is, the surface composition of one or more of the plurality of VOC sensors may be altered by including a catalytic material in the chemically sensitive membrane (i.e., active layer). In other words, the chemically sensitive film of the one or more VOC sensors may comprise a dopant. In some embodiments, the dopant may be, for example, a transition metal. For example, the dopant may be selected from the group comprising: platinum; palladium; molybdenum; tungsten; nickel; ruthenium; and osmium.

In step S206, one or more of the plurality of VOC sensors is heated to at least a first operating temperature. In particular embodiments, the operating temperature is between about 180 ℃ and about 400 ℃. In other embodiments, the operating temperature of one or more VOC sensors is maintained during subsequent steps of the method. In particular, the heating circuit of each VOC sensor can be used to measure and control the temperature of the VOC sensor throughout its operation.

In certain embodiments of the method 200, the method may include one or more calibration steps 208, including: contacting one or more of the plurality of VOC sensors with a sample fluid stream, the sample fluid stream being free of any target VOC (S210); measuring a baseline conductance of the one or more VOC sensors (S212); optionally, removing the fluid stream from contact with the one or more VOC sensors (S216); contacting one or more VOC sensors with a control fluid stream having a known concentration of a target VOC (S218); measuring a control conductance of each of the one or more VOC sensors (S220); calculating a specific net conductance value based on the measured control conductance of the VOC sensor and the known concentration of the target VOC within the control fluid stream (S222); and repeating at least steps S218 to S222 for a plurality of control fluid flows (S226). The calibration step 208 may also include: removing the fluid stream from contact with the one or more VOC sensors (S228); and adjusting the baseline conductance of the one or more VOC sensors after contacting the at least one target VOC (S230).

In step S210, one or more of the plurality of VOC sensors is contacted with a sample fluid stream. In a preferred embodiment, the sample fluid stream is a volume of air that can be tested by method 200 without any target VOCs.

In step S212, a baseline conductance of the one or more VOC sensors contacting the sample fluid stream is measured using the sensing circuitry of the VOC sensors. Because the film formed on the sensing circuitry of the VOC sensor is chemically sensitive (e.g., semi-conductive), the current flowing in the material is due to electrons in the conduction band of the film, which may be affected by the presence of undesirable and/or target compounds (e.g., target VOCs). Thus, after reaching the operating temperature and contacting the gas sample (i.e., the sample fluid stream) free of the marker gas (i.e., the fluid stream having at least one target VOC) in step S206, the resistance of the VOC sensor is measured and recorded as a baseline resistance or baseline conductance. In some embodiments, a set of baseline conductances ({ K }) _i ⁰ }) 214 is determined and includes a baseline conductance (e.g., K) for each of a plurality of VOC sensors ₁ ⁰ 、K ₂ ⁰ 、…K _n ⁰ )。

In step S216, the sample fluid stream no longer contacts the VOC sensors of the sensor array. In particular embodiments, this may include cleaning a chamber or reactor containing the sensor array and/or one or more VOC sensors.

In step S218, one or more VOC sensors are contacted with a control fluid stream (e.g., a marker gas) having a known concentration of at least one target VOC.

In step S220, a control conductance of each of the one or more VOC sensors in contact with the control fluid stream is measured. The resistance/conductance of the VOC sensor may change because contact control of fluid flow may make more or less electrons available for chemically sensitive membrane based conduction.

Then in step S222, a specific net conductance value for each of the one or more VOC sensors is determined based on the measured test conductance of the VOC sensors and the known concentration of the target VOC within the control fluid stream. As studied and disclosed herein, the amount of conductance change may be proportional to the gas concentration, and as used herein, specific net conductance ("SNC") refers to the proportionality coefficient. In particular embodiments, the first target VOC concentration of the control fluid stream is from about 10ppb to about 400ppb. In a preferred embodiment, the control fluid stream has a target VOC concentration of about 200ppb.

The resulting change between the baseline and control conductances measured for one or more of the multiple VOC sensors is determined and divided by a specified (i.e., known) concentration to give an SNC value (i.e., a measure of the sensitivity of the chip to the gas), typically expressed in units of "nano-mhos" or "nmho/ppb". Each chip has a different SNC for each target gas of interest in the application.

For further calibration, in step S226, at least steps S218-S222 may be repeated for additional control fluid flows to obtain a plurality of specific net conductance ("SNC") values for one or more VOC sensors, wherein each specific net conductance value for each VOC sensor corresponds to a different target VOC. In some embodiments, the plurality of SNC values is a set of SNC values ({ SNC _i,X ]) 224, and includes SNC values corresponding to one or more target VOCs for each of a plurality of VOC sensors (e.g., SNC for the first VOC sensor _1,X1 、SNC _1,X2 、…SNC _1,Xn (ii) a For the second VOC sensor, SNC _2,X1 、SNC _2,X2 、…SNC _2,Xn (ii) a Etc.) wherein X is _n Representing a particular target VOC.

The method 200 can also include a step (S230/S232) that includes adjusting a baseline conductance/resistance of one or more VOC sensors. For example, after contacting the target VOC(s), the VOC sensor may have a subsequent (i.e., post-contact) baseline conductance that is different from the baseline conductance before it contacts the target VOC(s). In particular embodiments, such a baseline conductance change may be obtained by adjusting the baseline conductance after contacting the target VOC (S) in steps S230/S232. During calibration 208, the control fluid flow may be removed (e.g., from the sensor array chamber) S228, and the conductance of the VOC sensor may be adjusted in step S230 by: the method further includes measuring the conductance of each VOC sensor to determine a post-contact conductance of the VOC sensor, comparing the post-contact conductance to baseline conductance 214, and heating one or more of the VOC sensors to at least a second operating temperature such that the conductance of each VOC sensor at the second operating temperature matches the corresponding baseline conductance 214 prior to contact. The second operating temperature of each VOC sensor may be higher or lower than the first operating temperature of the VOC sensor based on the measured post-contact conductance of the respective VOC sensor.

Turning to fig. 2B, after the calibration step 208, in step S232, the baseline conductance of the VOC sensor may be adjusted by: a sensor array chamber that is purged of the target VOC, measures the conductance of one or more VOC sensors, compares the measured conductance to a corresponding baseline conductance, and heats the one or more VOC sensors to at least a second operating temperature such that the conductance of each VOC sensor at the second operating temperature matches the corresponding baseline conductance 214.

After the adjusting step S232 or the heating step S206, the one or more VOC sensors are contacted with the target fluid stream at step S234. In certain embodiments, the target fluid flow is a sample of air taken from the vicinity of the stored product assessed as likely to be subject to infestation. Thus, the target fluid stream may comprise one or more target VOCs, such as semiochemicals, kairomones, and/or semaphores associated with one or more insects (e.g., SPI). For example, several pheromones and semiochemicals for certain SPIs are listed in tables 1 and 2 below:

TABLE 1 SPI and pheromones thereof

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TABLE 2 IMM pheromone and semiochemical components

In step S236, the signal conductance of the one or more VOC sensors is measured after the one or more VOC sensors contact the target fluid stream.

Then, in step S238, a set of conductance change values ({ Δ K) is determined for one or more VOC sensors of the sensor array _i }). In particular embodiments, for each VOC sensor, the conductance change value may be determined as follows:

ΔK _i ＝K _i -K _i ⁰

wherein i is an integer,. DELTA.K _i Is the value of the conductance change, K, of the VOC sensor i _i For the signal conductance measured by the VOC sensor i in the presence of a target fluid flow, K _i ⁰ Is the baseline conductance of the VOC sensor i.

In step S240, a concentration of a gas component ([ X ] of one or more target VOCs) within the target fluid stream is determined based on the set of conductance change values] _n ). In certain embodiments, more than one target VOC may be present in the target fluid stream, in addition to other background and/or interfering gases, which makes analysis difficult. In particular embodiments, the set of conductance change values and the one or more SNCs for each VOC sensor are based onDetermining a concentration ([ X) of a gas constituent of one or more target VOCs within a target fluid stream] _n ). In a further embodiment, the concentration of the gas constituent of the one or more target VOCs ([ X ] s) within the target fluid stream is determined by solving a system of equations, such as shown below] _n )：

ΔK ₁ ＝SNC _1A [A]+SNC _1B [B]+SNC _1C [C]+SNC _1D [D]+SNC _1E [E]+SNC _1F [F]

ΔK ₂ ＝SNC _2A [A]+SNC _2B [B]+SNC _2C [C]+SNC _2D [D]+SNC _2E [E]+SNC _2F [F]

ΔK ₃ ＝SNC _3A [A]+SNC _3B [B]+SNC _3C [C]+SNC _3D [D]+SNC _3E [E]+SNC _3F [F]

ΔK ₄ ＝SNC _4A [A]+SNC _4B [B]+SNC _4C [C]+SNC _4D [D]+SNC _4E [E]+SNC _4F [F]

ΔK ₅ ＝SNC _5A [A]+SNC _5B [B]+SNC _5C [C]+SNC _5D [D]+SNC _5E [E]+SNC _5F [F]

ΔK ₆ ＝SNC _6A [A]+SNC _6B [B]+SNC _6C [C]+SNC _6D [D]+SNC _6E [E]+SNC _6F [F]

Wherein Δ K _i Is the measured change in conductance of the sensor "i", which ranges from 1 to 6 _ij Is the "specific net conductance" of the sensor "i" upon contact with a gas "j" (e.g., a target VOC), which is a gas or gas class A, B, C or D, E, F, and [ X]The concentration of a gas a, B, C or D is expressed in units of gas volume ratio (i.e. liters of gas per liter of total atmosphere).

Although six target VOCs (i.e., a, B, C, D, E, and F) and six sensors (i.e., 1, 2,3, 4, 5, and 6) are described above, the number of target VOCs and the number of VOC sensors present in the analysis may vary from application to application, or from use to use, and is not limited to only six. Thus, it becomes possible to determine the concentration problems of several target VOCs and/or background and interfering gases present in a particular fluid stream.

In some embodiments, the method 200 may further include operating a user interface to communicate the analysis results (S242). That is, the apparatus provided in step S204 may further comprise a user interface configured to display the analysis results of the target fluid flow to an associated user. For example, the user interface may be configured to display or otherwise indicate the presence of pests, including the presence of one or more insects (e.g., SPI). The presence of an intrusion is indicated based on a predetermined threshold concentration, which may be related to the type of storage facility (e.g., in a trailer, a land/sea container, a bulk shipment, a packing batching tray, or a storage room) or the type of stored product being tested. The user interface may also be configured to display or otherwise indicate the level of insect presence based on the detected target VOC (e.g., the degree of infestation).

In particular embodiments, the user interface may be a dedicated screen, such as a TFT LCD screen, an IPS LCD screen, a capacitive touch screen LCD, an LED screen, an OLED screen, an AMOLED screen, or the like. In other embodiments, the user interface may include a wired or wireless communication protocol, such as bluetooth, BLE, wi-Fi, 3G, 4G, 5G, LTE, etc., and the user interface may be configured to communicate the analysis results to an auxiliary device (e.g., mobile phone, tablet, computer, etc.) of the associated user via the communication protocol.

In a preferred embodiment, the target fluid flow is a sample (or volume) of air taken from the vicinity of the stored product assessed as likely to be infested. In step S244, steps S232-S242 may be repeated by sampling multiple target fluid streams (e.g., air samples) from within multiple proximity to the stored product (S) being evaluated. That is, method 200 may also include identifying the source of the pest, for example, by detecting a target VOC gradient on two or more target fluid streams (e.g., a first target fluid stream, a second target fluid stream, a third target fluid stream, etc.) at different distances from the stored product(s).

In other embodiments of the method 200, the apparatus provided in step S204 may further comprise a controller operatively connected to the sensor array and the user interface, wherein the controller comprises a processor configured to perform one or more of the steps of the method 200 described above, and a memory configured to store one or more of the data types described above. Further, the memory may be configured to store instructions for performing one or more steps of the method 200.

In step S250, the method 200 may end.

These and other aspects of the apparatus for implementing the

methods

100, 200 described herein may be more readily understood by reference to the following discussion and the various figures discussed therein.

Apparatus and system

Disclosed herein are devices and systems that perform the above-described

methods

100, 200. In particular, discussed herein are highly sensitive and highly selective devices for detecting one or more target volatile organic compounds ("VOCs") within a target fluid stream (e.g., certain semiochemicals, kairomones and/or pheromones of various stored product insects ("SPIs"). In addition, the devices and systems may be compact and light enough to be easily carried and hand-held.

Referring to fig. 3, a block diagram of an apparatus 300 and a system 302 configured to perform the methods disclosed herein is shown, according to one embodiment of the present application. In particular, the device 300 includes a sensor array 304 having a plurality of VOC sensors 306. The plurality of VOC sensors 306 of the sensor array 304 may comprise about two to about ten VOC sensors, including three, four, five, and six VOC sensors. In particular embodiments, sensor array 304 may be enclosed in a chamber (or reactor) 308, with sensor 306 exposed to (i.e., in contact with) the desired environment within chamber 308. The chamber may have an inlet 310 and an outlet 312, the inlet 310 being configured to receive a fluid flow 314 from outside the chamber, the outlet 312 being configured to release a fluid flow 316 in the chamber 308.

As shown in fig. 4A and 4B, which illustrate a first side (fig. 4A) and a second side (fig. 4B) of a single VOC sensor 306 of a sensor array 304, the VOC sensor 306 may include a substrate 31 having a first side 320 and a second side 3228. The substrate 318 may be, for example, a ceramic material, or may be alumina (Al) ₂ O ₃ ) A wafer or a silicon wafer. In particular embodiments, substrate 318 may have an overall width of about 5mm to about 20mm, an overall height of about 4.3mm to about 20mm, and an overall thickness of about 0.32mm to about 0.65 mm. The VOC sensor 306 can include a resistive heater circuit formed on a first side 320 of the substrate 318, a sensing circuit 326 formed on a second side 322 of the substrate 318, and a chemically sensitive film 328 formed on the sensing circuit 326 located on the second side 322 of the substrate 318.

Resistive heater circuit 324 may be formed on substrate 318 using, for example, photolithography with heater circuit materials. In some embodiments, the heater circuit material may include platinum. In particular embodiments, the heater circuit material may be a platinum ink including about 70wt% to about 95wt% platinum.

The heater circuit material may be, for example, lithographically patterned into a desired pattern on the substrate 318. In a particular embodiment, the resistive heater circuit 324 of at least one of the plurality of VOC sensors 306 of the sensor array 304 can have a serpentine (i.e., serpentine) pattern across a portion of the substrate 318. For example, in some embodiments, resistive heater circuit 324 may have a longitudinal trace width 330 of about 0.288mm to about 0.352mm. In a further embodiment, resistive heater circuit 324 may have a longitudinal trace pitch 332 of, for example, about 0.333mm to about 0.407mm. In still further embodiments, at least a portion of resistive heater circuit 324 may have a trace height 334 of about 3.80mm to about 3.96mm, an outer trace width 336 of about 4.40mm to about 4.58mm, and a trace thickness (i.e., depth) of about 0.19mm to about 0.24mm, including about 0.21 mm.

VOC sensor 306 may also include one or

more terminals

338, 340 on first side 320 of substrate 318. For example, as shown in fig. 4A, the first side 320 of the substrate 318 includes at least two

terminals

338, 340, each of which is operatively connected to a portion (e.g., opposite ends) 342, 344, respectively, of the resistive heater circuit 324.

Turning now to FIG. 4B, sensing circuitry 326 may be formed on substrate 318 using, for example, photolithography with sensing circuitry material. In some embodiments, the sensing circuit material may include platinum. In particular embodiments, the sensing circuit material can include platinum ink having about 70wt% to about 95wt% platinum.

The sensing circuit material may be, for example, lithographically patterned into a desired pattern on the substrate 318. In a particular embodiment, the sensing circuit 326 includes a first sensing element 346 and a second sensing element 348 that form a pair of extended interdigitated contacts (i.e., alternating, unconnected, closely proximate contacts). The first sensing element 346 can include a plurality of extended contacts 350, wherein each contact 350 has a lateral trace width 354 of about 0.162mm to about 0.198mm, a lateral trace pitch 356 of about 0.738mm to about 0.902mm, and a trace thickness (i.e., depth) of about 0.19mm to about 0.24 mm. For example, the contacts 350 may have a lateral trace width 354 of about 0.18mm, a lateral trace pitch 356 of about 0.82mm, and a trace thickness of about 0.21 mm.

Similarly, the second sensing element 348 may include a plurality of extended contacts 352, wherein each contact 352 has a lateral trace width 358 of about 0.162mm to about 0.198mm, a lateral trace pitch 360 of about 0.738mm to about 0.902mm, and a trace thickness (i.e., depth) of about 0.19mm to about 0.24 mm. For example, the contact 354 may have a lateral trace width 358 of about 0.18mm, a lateral trace pitch 360 of about 0.82mm, and a trace thickness of about 0.21 mm.

In some embodiments, the first and

second sense elements

346, 348 can include at least three

contacts

350, 352, respectively, with a lateral trace pitch 362 of about 0.288mm to about 0.352mm (including about 0.32 mm) between each contact 350 of the first sense element 346 and each contact 352 of the second sense element 348. Further, each of the

contacts

350, 352 may have a longitudinal trace length 364 of about 3.0mm to about 4.0mm (including about 3.8 mm).

The second side 322 of the substrate 318 may also include one or

more terminals

366, 368 that are operatively connected to

portions

370, 372 of the sensing circuit 326.

In addition,

contacts

350, 352 of sensing circuit 326 may be coated with a coating composition to form chemically sensitive membrane 328. In some embodiments, the coating composition may include a gel, and the film 328 may be formed by: the coating composition is applied to a portion of the substrate 318 (e.g., the portion covering the contacts 350, 352), and then dried and calcined at an elevated temperature (e.g., about 400 ℃ to about 900 ℃ (including about 500 ℃ to about 700 ℃).

In particular embodiments, film 328 may be a metal oxide film, such as tin oxide (SnO) ₂ ) A semiconductor film. In such embodiments, the coating composition may include tin oxide produced using a water-based gel. In certain embodiments, the gel is prepared by a sol-gel process involving SnCl ₄ To form an acidic tin solution, which is neutralized to produce SnO ₂ And (4) gelling. Then, for example, by dissolving aqueous SnO ₂ Gel spinning (spin coating) onto the sensor side 322 of the substrate 318, drying the sensor 306 at a first temperature, and then calcining at a second temperature to form nanocrystalline SnO on the substrate 318 ₂ And a membrane 328. In particular embodiments, the first temperature at which drying occurs is from about 100 ℃ to about 150 ℃, and may preferably be about 130 ℃. In other embodiments, the second temperature at which the calcination is performed is from about 400 ℃ to about 900 ℃, and may preferably be from about 700 ℃ to about 800 ℃. Importantly, these temperature ranges produce a pore size distribution and particle size distribution that provides excellent sensitivity in the chemically sensitive membrane 328.

Due to the chemical structure of the target VOC and the operating conditions of each VOC sensor 306, when the target VOC (e.g., the marker gas) contacts the chemically sensitive membrane 328, the number of electrons available in the conduction band of the membrane 328 may be affected (i.e., increased or decreased). In particular embodiments, the one or more target VOCs may be a "reducing gas" that provides additional electrons to the conduction band of film 328, thereby reducing the resistance of film 328, which may then be measured as a change in the conductance of film 328. This effect can be seen in fig. 19A to 19G.

Certain semiochemicals, semiochemicals and kairomones of interest may comprise a six-membered carbocyclic ring and one or more carbonyl groups (— C = O). This is the region of the molecule where excess electron density is located that allows interaction with semiconductor film 328 to contribute charge carriers to the conduction band of film 328 (i.e., to reduce the resistance of film 328). The chemical structures of the two semiochemicals are shown in table 3 below:

TABLE 3 semiochemical/kairomone chemical structures

In a preferred embodiment, the sensor array 304 includes a plurality of different VOC sensors 306. That is, the composition of one or more of the plurality of VOC sensors 306 varies and is optimized for specific detection needs. For example, the coating composition used to form film 328 may include one or more catalysts or dopants (e.g., dopants), which may be added at the time of preparing the gel coat composition. In some embodiments, the coating composition comprises a dopant. In some embodiments, the dopant can be, for example, a transition metal. For example, the dopant may be selected from the group comprising: platinum; palladium; molybdenum; tungsten; nickel; ruthenium; and osmium. As a result of the addition of the dopant to the film 328 of the VOC sensors 306, each VOC sensor 306 may be optimized for a given gas or target VOC.

In particular embodiments, the device 300 may include a plurality of VOC sensors 306, wherein at least one VOC sensor 306 is optimized for a particular gas or target VOC by adding a catalyst or dopant (i.e., dopant). In other embodiments, each VOC sensor 306 present in the device 300 is optimized for a particular gas or target VOC by adding a catalyst or dopant (i.e., dopant). For example, in particular embodiments, the sensor array 304 may include a first VOC sensor 306 configured to detect IMM larvae semiochemicals, a second VOC sensor 306 configured to detect adult IMM pheromones, a third VOC sensor 306 configured to detect one or more egg-specific VOCs, and one or more VOC sensors 306 configured to detect potential interfering and/or background gases; however, other combinations and numbers of VOC sensors 306 are also contemplated. In one such embodiment, the sensor array 304 may include first and second VOC sensors 306 configured to detect IMM larva semiochemicals, a third VOC sensor 306 configured to detect egg-specific VOCs, a fourth VOC sensor 306 configured to detect adult IMM semiochemicals, and up to three VOC sensors 306 configured to target potentially interfering and/or background gases. Potential interfering and/or background gases may include, for example, hydrocarbons, alcohols, esters, and/or aldehydes.

Each VOC sensor 306 of device 300 may be positioned within chamber 308 such that chemically-sensitive membrane 328 can be exposed to a fluid flow entering chamber 308. Referring to fig. 5, in a particular embodiment, each VOC sensor 306 may be suspended in, for example, a support 500 that supports the sensor 306 using

wire bonds

502, 504, 506, 508, 510, 512 and connects the various sensor 306

terminals

340, 342, 366, 368 to

contacts

514, 516, 518, 520, 522, 524 of the sensor support 500.

With further reference to fig. 6, a side view of an apparatus 300 according to certain aspects of the present disclosure is shown. In particular, device 300 shows a sensor array 304 that includes six VOC sensors 306 (not visible) suspended by a sensor holder 500 within a chamber 308. Further, according to some embodiments, a portion 526 of each sensor holder 500 may operably engage an adapter 528, which adapter 528 operably connects the holder 500 and the VOC sensor 306 to a circuit board 530 of the device 300, which allows, for example, power to be supplied to the VOC sensor 306 and allows measurements to be taken.

In other words, the sensor array 304 may be operably connected to a controller 374, the controller 374 being configured to perform one or more steps of the method described above. In particular, the controller 374 may be configured to: heating one or more of the plurality of VOC sensors 306 to at least a first operating temperature; measuring the conductance of one or more of the plurality of VOC sensors 306; determining a set of conductance change values corresponding to each of the one or more VOC sensors 306 contacting the fluid stream; and determining a concentration of the one or more target VOC gas constituents within the fluid stream based on the set of conductance change values.

Referring to fig. 7, a perspective view of an apparatus 300 is shown, according to certain aspects of the present disclosure. As shown, the housing 708 of the device 300 can have a height 709, a width 711, and a depth 713, each of which can be less than 5 inches. In some embodiments, the housing 708 of the device 300 can have a height 709 of about 3 inches to about 4 inches (including about 3.4 inches), a width 709 of about 4 inches to about 5 inches (including about 4.88 inches), and a depth 713 of about 4 inches to about 5 inches (including about 4.17 inches). However, other dimensions are also contemplated.

Returning to FIG. 3, additional components of intrusion detection system 302 are described in accordance with various aspects of the present application. A system 302 for identifying pests of a stored product is provided, the system 302 including a sensor array 304 as previously described. Moreover, in certain embodiments, the system 302 includes a test chamber 308 enclosing the sensor array 304, an air delivery unit 376, and a controller 374 operatively connected to the air delivery unit 376 and the sensor array 304.

In various embodiments, air delivery unit 376 may include a valve 378 for controlling fluid flow through system 302, a pump 380 for retrieving (or drawing) fluid flow from outside system 302 and delivering (or pushing) fluid flow through system 302, and a fluid flow sensor 382 for measuring the amount (e.g., volume) of fluid retrieved by air delivery unit 376. In certain embodiments, the fluid flow sensor 382 can be a mass flow control valve or a differential pressure sensor. In other embodiments, the valve 378 and the pump 380 may be user actuated. That is, an associated operator of system 302 may use air delivery unit 376 to direct (e.g., physically trigger) the withdrawal of the external fluid flow.

The air transfer unit 302 may also define fluid flow paths for fluid flow 384 from outside the system 302 to the flow 314 entering the inlet 310 of the device 300, and to the flow 316 exiting the outlet 312 of the device 300. Portions of the fluid streams 314, 316, 384 may be transported along a fluid stream carrier (e.g., a polymer conduit).

Further, the air delivery unit 376 may be operably connected to the controller 374 such that the controller 374 may operate the air delivery unit 376 to retrieve the fluid stream from the chamber 308 and deliver the fluid stream to the chamber 308, where the fluid stream may be in fluid contact with the VOC sensor 306. In certain embodiments, the controller 374 may, for example, measure an amount (e.g., volume) of fluid flow into the system 302 and instruct the air delivery unit 376 (e.g., the pump 380 and/or the valve 378) to stop drawing fluid (e.g., air) once the measured amount reaches a predetermined threshold. In some embodiments, the predetermined threshold is a volume sufficient for the device 300 to detect and measure the presence of one or more target VOCs in the fluid stream.

The controller 374 of the system 302 may be operably connected to the air delivery unit 376 and the sensor array 304, and may include a processor and memory. The controller 374 may also be configured to: operating the air transport unit 376 to retrieve a fluid stream (e.g., fluid stream 378) from outside the system 302 and deliver the fluid stream (e.g., fluid stream 314) to the test chamber 308, wherein the plurality of VOC sensors 306 are in fluid contact with the fluid stream 314; operating the sensor array 304 to heat the one or more VOC sensors 306 to at least a first operating temperature and to measure the conductance of one or more of the plurality of VOC sensors 306; determining a set of conductance change values corresponding to each of the one or more VOC sensors 306; and based on the set of conductance change values, the gas constituent concentration of the one or more target VOCs within the fluid stream 314 is determined.

In some embodiments, the system 302 also includes user interface component(s) 380. User interface 380 may be operatively connected to controller 374, and controller 374 may be configured to operate user interface 380 to display and/or communicate results of tests performed by system 302 to an associated user. The user interface 380 may be a dedicated display 382 visible to a user or operator of the system 302, such as a display including a TFT LCD screen, an IPS LCD screen, a capacitive touch screen LCD, an LED screen, an OLED screen, an AMOLED screen, or the like. In other embodiments, the user interface 380 may include a wired or wireless communication protocol 384, such as bluetooth, BLE, wi-Fi, 3G, 4G, 5G, LTE, etc., and the user interface 380 may be configured to communicate the analysis results to an associated user's auxiliary device 386 (e.g., mobile phone, tablet, computer, etc.) via the communication protocol.

The system 302 may also include a power supply 388 operably connected to at least one of the air delivery unit 376, the device 300, the controller 374, and the user interface 380. The power supply 388 may be configured to deliver power to one or more components of the system 302, while the controller 374 may be configured to operate the power supply 388. In certain embodiments, the power supply 388 may be integrated into the system 302. In other embodiments, the power supply 388 may be a removable external accessory. In some embodiments, the power supply 388 may be a rechargeable power supply 388.

The various components of the described system are now discussed in more detail with reference to fig. 8. As shown, fig. 8 illustrates a block diagram of a system 700 for identifying pests of stored products by, for example, detecting the presence and measuring the levels of one or more target VOCs. The system 700 includes a sensor array 306, a controller 374 having a processor 702, a memory 704, and one or more input/output (I/O) interfaces 706, 708. The bus 710 may operatively connect the processor 702, the memory 704, and the I/O interfaces 706, 708 together. The memory 704 includes instructions 712 for performing one or more steps of the methods disclosed herein, and the processor 702 in communication with the memory 704 is configured to execute the instructions for performing the one or more steps.

As shown, the system 700 may also include a sensor array 304, the sensor array 304 including a plurality of VOC sensors 306, as well as an air delivery unit 376 and a user interface 380. Processor 702 may also control the overall operation of system 700, including the operation of sensor array 304, air delivery unit 376, and user interface 380.

Memory 704 may represent any type of non-transitory computer readable medium, such as Random Access Memory (RAM), read Only Memory (ROM), magnetic disk or tape, optical disk, flash memory, or holographic memory. In one embodiment, memory 704 comprises a combination of random access memory and read only memory. In some embodiments, the processor 702 and the memory 704 may be combined in a single chip. Input/output (I/O) interfaces 706, 708 allow controller 374 to communicate with other components of system 700, such as sensor array 304, fluid flow sensor 382, air transport unit 376, and user interface 380, via wired or wireless connections. The digital processor 702 may be implemented, for example, by a single-core processor, a dual-core processor (or more generally, a multi-core processor), a digital processor, and a cooperative method co-processor, digital controller, and the like.

As used herein, the term "software" is intended to encompass any collection or set of instructions executable by a computer or other digital system in order to configure the computer or other digital system to perform a task for which the software is intended. The term "software" is intended to encompass such instructions stored in a storage medium such as RAM, hard disk, optical disk, and the like, and is also intended to encompass so-called "firmware", i.e., software stored on ROM and the like. Such software may be organized in various ways and may include software components organized as libraries, internet-based programs stored on remote servers, and the like, source code, interpreted code, object code, directly executable code, and the like. It is contemplated that the software may invoke system-level code or other software residing on the server or elsewhere to perform some function.

In various embodiments, instructions 712 of controller 374 may include, for example, a conductance change module 714, a specific net conductance ("SNC") data module 716, an air flow management module 718, an operating temperature module 720, a VOC concentration module 722, and a report output module 724.

The conductance change module 714 may be configured to measure the conductance of one or more VOC sensors 306 of the sensor array 304 and record conductance data 728 in the memory 704. That is, in particular embodiments, conductance change module 714 may be configured to instruct processor 702 to measure changes in the bulk resistance of chemically-sensitive film 328 of one or more VOC sensors 306 using respective sensing circuitry 326. Accordingly, the conductance change module 714 may be configured to measure and receive conductance signals from the VOC sensors 306 of the sensor array 304 via the I/O interface 706 and store the conductance as conductance data 728 in the memory 306. The conductance-varying module 714 may also be configured to, for example, minimize electronic noise and drift of the conductance signal measured from the VOC sensor 306 to ensure accurate and precise measurements. In some embodiments, the conductance change module 714 may be configured to apply, for example, signal models and/or algorithms to manage or eliminate problems of conductance drift and electronic noise in the sensor conductance measurements. In other embodiments, the conductance change module 714 may be configured to adjust the conductance values of the one or more VOC sensors by measuring the conductance of the VOC sensors and increasing and/or decreasing the operating temperature of the one or more VOC sensors (via the operating temperature module 720) until the conductance values of the VOC sensors match the previously determined baseline conductance values.

As previously described, the SNC data module 716 may be configured to determine the specific net conductance ("SNC") of one or more VOC sensors 306 of the sensor array 304. In particular, SNC data module 716 and conductance change module 714 may operate to measure and receive certain conductance signals (e.g., conductance values of a VOC sensor contacting a control fluid stream and/or a sample fluid stream absent the target VOC) through I/O interface 706. The SNC data module may then determine a set of SNC values for the VOC sensors 306 and store the set of SNC values as SNC data 726 in the memory 704.

The air flow management module 718 may be configured to operate the air delivery unit 326 to retrieve a fluid flow (e.g., fluid flow 384), deliver the fluid flow to the device 300, and purge the fluid flow (e.g., fluid flow 316) from the system 302. In particular, airflow management module 718 may be configured to receive airflow data 730 from fluid flow sensor 382 of air transport unit 376 via I/O interface 706. For example, airflow data 730 may include a fluid intake threshold (e.g., volume) and measurements from fluid flow sensor 382 that may be stored in memory 704. Additionally, the air flow management module 718 may be configured to operate an air delivery unit 376 including a valve 378 and a pump 380, as well as the inlet 310 and outlet 312 that control the fluid flow path through the system 302.

The operating temperature module 720 can be configured to operate the heater circuit 324 of the VOC sensors 306 of the sensor array 304 via the I/O interface 706. In particular, the operating temperature module 720 may be configured to heat the one or more VOC sensors 306 to at least a first operating temperature and at least a second operating temperature by instructing the heating circuit 324 to apply power to the VOC sensors 306. The operating temperature module 720 can also be configured to monitor the temperature of each VOC sensor 306 of the sensor array 304 and adjust the power supplied to adjust the operating temperature(s) of the VOC sensors 306. The temperature module 720 can store the set point operating temperature(s) of the VOC sensor 306, as well as the measured temperature, as the temperature 732 in the memory 704.

As described above, the VOC concentration module 722 may be configured to determine a gas constituent concentration of one or more target VOCs in a fluid stream. The one or more target VOCs can be in gaseous form in a fluid stream (e.g., an air stream). In particular embodiments, the one or more target VOCs are at least one of: a pheromone; a semiochemical; and kairomones. In further embodiments, at least one of the one or more target VOCs within the fluid stream may be selected from the group consisting of: 11, 13-hexadecadienal, 4, 8-dimethyldecanal; (Z, Z) -3,6- (11R) -dodecen-11-olide; (Z, Z) -3, 6-dodecenolactone; (Z, Z) -5,8- (11R) -tetradecadiene (Tetradecadien) -13-lactone; (Z) -5-tetradecene-13-lactone; (R) - (Z) -14-methyl-8-hexadecenal; (R) - (E) -14-methyl-8-hexadecenal; gamma-ethyl-gamma-butyrolactone; (Z, E) -9, 12-n-tetradecadienylacetic acid; (Z, E) -9, 12-tetradecadien-1-ol; (Z, E) -9, 12-tetradecadiene; (Z) -9-tetradecene acetate; (Z) -11-acetic acid hexadecenyl ester; (2S, 3R,1' S) -2, 3-dihydro-3, 5-dimethyl-2-ethyl-6 (1-methyl-2-oxobutyl) -4H-pyran-4-one; (2S, 3R,1' R) -2, 3-dihydro-3, 5-dimethyl-2-ethyl-6 (1-methyl-2-oxobutyl) -4H-pyran-4-one; (4S,6S,7S) -7-hydroxy-4, 6-dimethylnonan-3-one; (2s, 3s) -2, 6-diethyl-3, 5-dimethyl-3, 4-dihydro-2H-pyran; 2-palmitoyl-cyclohexane-1, 3-dione; and 2-oleoyl-cyclohexane-1, 3-dione. However, other pheromones, semiochemicals and kairomones are also contemplated. The determined concentration of one or more of these target VOCs can be stored in memory as VOC data 734.

Report output module 724 may be configured to generate desired system output 738 and to operate user interface 380 via I/O interface 380 to communicate output 738 to an associated user of system 302. In particular embodiments, user interface 380 may be a dedicated display or may be an auxiliary user device (e.g., a PC, such as a desktop, laptop, palmtop, portable Digital Assistant (PDA), server computer, cellular telephone, tablet computer, mobile device, etc., or a combination thereof). In some embodiments, the user interface 380 may include a speaker or speaker system. Thus, in some embodiments, the I/O interface 708 may be a wired communication interface. In other embodiments, the I/O interface 708 may include a wireless communication component, and communication with the user interface 380 may occur via a wireless communication protocol, such as bluetooth, BLE, wi-Fi, 3G, 4G, 5G, LTE, and so forth.

In either case, a system output 738, such as a graph, chart, table, or data set (e.g., illustrating the determined VOC data), may be communicated via the user interface 380 in various embodiments. In some embodiments, the output 738 may include audible components, such as audio tones, tone groups, or audible words, that may be communicated via a speaker or speaker system of the user interface 380. The audible output component may be a tone that sounds at a frequency that varies based on the detected concentration of the gas constituent(s) of the target VOC(s) (e.g., the frequency increases as the level of detection becomes higher). In certain embodiments, output 738 includes a determination of whether a pest is likely to be present in the stored product. In a further embodiment, output 738 may include an estimate of the cause of the possible intrusion (e.g., based on the VOC data, identifying one or more particular SPIs). In still further embodiments, output 738 may include recommendations for taking remedial action to preserve the value of the stored product, such as fumigation.

Examples of the invention

The following specific examples describe novel aspects of the present disclosure and processes used therein. It is intended to be illustrative only and should not be construed as limiting the invention in its broadest aspect.

Example 1

Referring to fig. 9A-9D, a graph of laboratory bench testing of various embodiments of VOC sensor chips and sensitivity of the VOC sensor chips to pheromones is provided. Adult pheromones were made into test gas at a concentration of 2ppm in a31 compressed gas cylinder under dry nitrogen. The test gas was diluted with additional dry nitrogen to obtain a gas stream having a pheromone concentration of between 100ppb and 300 ppb. The gas stream was injected into a pre-prototype apparatus and the net conductance determined. The following graph shows the response of five different sensors, one without catalyst and four with catalysts palladium, platinum, osmium and tungsten. The tungsten catalyst provided excellent sensitivity for IMM pheromones (fig. 9A), tobacco beetle pheromones (fig. 9C), and warehouse beetle pheromones (fig. 9D). The palladium catalyst showed excellent sensitivity to red flour beetle pheromones (fig. 9B). Other catalysts have less sensitive to pheromone response.

Example 2

With reference to fig. 10A to 10C, 11A to 11C, and 12A to 12C, experimental results of field tests of the response of the sensor chip to the headspace on the product with insects are provided. In the field test, headspace gas above a 10 pound sample of clean white wheat flour was injected into the pre-prototype apparatus to establish a baseline resistance value. Once the baseline resistance values were established, vials containing different numbers of four live insects, IMM, red flour beetle, warehouse beetle, and cigarette beetle, were injected with headspace gas over a 10 pound sample of clean white wheat flour. Resistance data for headspace gas on live insect-added products without catalytic chips (fig. 10A-10B), with platinum catalytic chips (fig. 11A-11C), with osmium catalytic chips (fig. 12A-12C), and with tungsten catalytic chips (fig. 13A-13C) are shown.

As seen in each case, the decrease in resistance is evident as the insect population increases. Additional insects produce additional pheromones in the headspace. Higher pheromone concentrations result in a decrease in sensor chip resistance. Thus, the sensor chip is capable of generating a signal based on the insect population. The signal can be analyzed and correlations between insect populations and the signal can be established.

With respect to fig. 14A to 14D, graphs showing the analysis results of the above data are provided. The raw data are analyzed by converting the chip resistance value R into a chip conductance value (mathematically denoted as K). By conducting K from the chip in the presence of insects _g Minus the chip conductance K in the absence of insects _b To determine the net conductance. The net conductance is mathematically expressed as Δ K. Curves of Δ K versus insect numbers are shown in fig. 14A to 14D. These curves therefore allow the selection of the optimal catalyst for each pheromone: for example, catalyst-free chips for IMM; osmium catalyst chips for warehouse beetles; and a catalyst-free chip for cigarette beetles.

Example 3

In a third test, embodiments of the present disclosure were used to detect pheromones and semiochemicals released by live adult female IMM, larvae, and larvae in cocoons in stored food products. Two 10 gallon galvanized drums filled half of the white wheat flour (about 25 pounds). One of the barrels was used as a control and without any insects, while larvae of adult female IMM, IMM larvae, and cocoons were placed in the other barrel. A device according to one aspect of the present disclosure is connected to these drums by stainless steel tubing and a valve system, preventing contamination between the "reference" drum and the drum containing the insects. The pot containing the adults, larvae, and larvae from the cocoons was placed in a laboratory bucket.

First, the insect detection device obtains a baseline resistance reading by sampling the headspace gas from a "reference" tank, i.e., by measuring the conductance to determine the baseline conductance of the VOC sensor when the VOC sensor is in an environment without any target VOC. A baseline conductance/resistance reading is recorded for about 30 minutes or more.

The insect detection device then samples the headspace gas from the bucket containing the insects and records the resistance/conductance measurements of the VOC sensor for about 30 minutes or more. Referring to fig. 15, an example of a VOC sensor response is shown.

These steps were repeated several times for live larvae, larvae in cocoons, and adult females. The following table summarizes the tests performed:

for each of the larvae, larvae in the cocoons, and adult IMM, the "known" insect population introduced into the experimental bucket is compared to the calculated or "predicted" population of insects present. As described above, the resistance data measured by the device is processed according to one embodiment of the present disclosure. In particular, the predicted insect count is derived from a correlation curve created to show the change in resistance as the sample fluid flow changes from the reference bucket to the experimental bucket. To create a correlation curve, the signal (net R) must be determined every time an insect is present. The signal is the difference between the resistance of the chip in the absence of insects (i.e., the baseline conductance) and the resistance in the presence of insects. Since the baseline resistance varies with time, the baseline resistance is expected to be calculated using an equation derived by plotting a selected baseline resistance value versus time in the absence of insects. For example, fig. 16A-16C show plots of catalyst-free chips for three insect maturation stages. Then, a correlation curve is created for each chip. For example, the curves for the catalyst-free chips are shown in fig. 17A-17C as a quadratic fit.

As shown above, there is good agreement between the known and predicted quantities, with some variation when the analyte (i.e., VOC) concentration is expected to be very low. It is believed that the sensor device responds to adult female pheromones, larval semiochemicals 2-palmitoyl-1, 3-cyclohexanedione, cocoon 2-oleoyl-1, 3-cyclohexanedione, and 2-palmitoyl-1, 3-cyclohexanedione. Larvae cocoon using their jaw secretions (i.e., saliva) with a high concentration of 2-oleoyl-1, 3-cyclohexanedione, and their resulting feces contain a high concentration of 2-palmitoyl-1, 3-cyclohexanedione. There was some overestimation of live larvae and some underestimation of adult moths. It should be noted, however, that pheromone and semiochemical generation will vary over time of day and therefore not always be as consistent as the flow of analytes in a simulated environment.

Example 4

In a fourth test, embodiments of the present disclosure were used to detect adult females, larvae, and larvae in cocoons of Navel Oranges (NOW) in stored food products. Several one quart glass jars were each filled with a small amount of white wheat flour as shown in the following table:

one tank without insects, larvae, pheromones, and semiochemicals was used as a reference tank or control tank, while the other tanks contained insects. First, a baseline conductance is determined by sampling the headspace of a reference tank. Then, a fluid flow sample from the headspace of one of the experimental tanks (e.g., ex.1 to ex.8) will be tested. Data obtained using a palladium catalyst chip operated at 300 ℃ is shown in fig. 18. In particular, the vertical arrows indicate the time at which the headspace air starts to flow from the tank containing the insects. As can be seen, an immediate decrease in resistance indicates a transient response of the sensor chip to the analyte VOC. As is clear from this data, headspace air at 100 adults, 100 larvae, 100 cocoons, and 2 times (2X) egg count brings greater resistance change than headspace air at 50 adults, 50 larvae, 50 cocoons, and 1 times (1X) egg count. That is, the signal is proportional to the population or number of adults, larvae, cocoons, and eggs.

The present description has been described with reference to preferred embodiments. Obviously, modifications and alterations will occur to others upon reading and understanding the specification. It is intended that the invention be construed as including all such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof. That is, it will be appreciated that various of the above-described and other features and functions, or alternatives thereof, may be desirably combined into many other different systems or applications, and that various presently unforeseen or unanticipated alternatives, modifications, variations or improvements therein may be subsequently made by those skilled in the art which are also intended to be encompassed by the following claims.

Claims

1. A device for detecting one or more target Volatile Organic Compounds (VOCs) within a target fluid stream, the device comprising:

a sensor array having a plurality of VOC sensors, wherein each VOC sensor comprises:

a substrate;

a resistive heater circuit formed on a first side of the substrate;

a sensing circuit formed on a second side of the substrate; and

a chemically sensitive film formed on the sensing circuit at the second side of the substrate;

wherein at least one VOC sensor of the plurality of VOC sensors is configured to detect the presence of insect egg-specific VOCs.

2. The device of claim 1, wherein the sensor array comprises 2 to 10 VOC sensors.

3. The device of claim 1, wherein the resistive heater circuit of at least one of the plurality of VOC sensors has a serpentine pattern with a longitudinal trace width of 0.288mm to 0.352mm and a longitudinal trace pitch of 0.333mm to 0.407mm.

4. The device of claim 1, wherein said sensing circuitry of at least one of said plurality of VOC sensors comprises first and second sensing elements forming a pair of extended interdigitated contacts;

wherein the first sensing element comprises a plurality of extended contacts, each contact having a transverse trace width of 0.162mm to 0.198mm, and a transverse trace pitch of 0.738mm to 0.902 mm; and

wherein the second sensing element comprises a plurality of extended contacts, each contact having a transverse trace width of 0.162mm to 0.198mm, and a transverse trace pitch of 0.738mm to 0.902 mm.

5. The apparatus of claim 4, wherein each of the first and second sensing elements comprises at least three contacts, and wherein the sensing circuit has a lateral trace pitch between each extended contact of the first and second sensing elements of 0.288mm to 0.352mm.

6. The apparatus of claim 1, wherein at least one of the resistive heater circuit and the sensing circuit is formed from a composition comprising platinum, and the chemically sensitive film is a nanocrystalline tin oxide film formed from an aqueous tin oxide gel.

7. The device of claim 1, wherein the chemically sensitive film comprises a dopant selected from the group comprising: platinum; palladium; molybdenum; tungsten; nickel; ruthenium; and osmium.

8. The apparatus of claim 1, wherein the sensor array is operably connected to a controller configured to:

measuring the conductance of one or more of the plurality of VOC sensors;

determining a set of conductance change values corresponding to each of the one or more VOC sensors contacting the target fluid stream; and

determining a concentration of a gas component of the one or more target VOCs within the target fluid stream based on the set of conductance change values.